This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A253445 #17 Sep 08 2022 08:46:10
%S A253445 11,44,99,1616,2525,3636,4949,6464,8181,100100,121121,144144,169169,
%T A253445 196196,225225,256256,289289,324324,361361,400400,441441,484484,
%U A253445 529529,576576,625625,676676,729729,784784,841841,900900,961961,10241024,10891089,11561156
%N A253445 a(n) = concatenation of n^2 with itself.
%H A253445 Aaron Toponce, <a href="/A253445/b253445.txt">Table of n, a(n) for n = 1..10000</a>
%F A253445 a(n) = A020338(n^2) = n^2 * (1 + 10^(A004216(n^2)+1)).
%p A253445 seq(n^2*(1+10^(1+ilog10(n^2))),n=1..100); # _Robert Israel_, Jan 02 2015
%t A253445 Table[FromDigits[Join[IntegerDigits[n^2], IntegerDigits[n^2]]], {n, 40}]
%o A253445 (Magma) [Seqint(Intseq(n^2) cat Intseq(n^2)): n in [1..40]];
%o A253445 (PARI) vector(100,n,eval(concat(Str(n^2),Str(n^2)))) \\ _Derek Orr_, Jan 02 2015
%Y A253445 Cf. A000290, A020338, A175605.
%K A253445 nonn,base,easy
%O A253445 1,1
%A A253445 _Vincenzo Librandi_, Jan 02 2015